Various systems and facilities intake large quantities of water from various exposed natural and other above-ground water sources, such as rivers, lakes, oceans, reservoirs, irrigation and flood water canals, outdoor water parks, other water conveyance structures, and the like. Examples of such systems and facilities include hydroelectric plants, pulp and paper mills, steel mills, petro-chemical plants, municipal water systems and waste water plants, nuclear and other energy facilities that use the water for cooling or for other purposes, other water filtering or screening facilities, etc. In all such systems it is important to screen naturally occurring debris and refuse, i.e. trash, found in the exposed above-ground water source from the flow of water that is taken into and employed by the system or facility.
Various screening systems are known and used for preventing debris found in exposed above-ground water sources from entering into the systems or facilities described above. An exemplary screening system of this type is known as an intake rack system or trash rack. Intake rack systems typically provide screening using a series of vertically oriented parallel blades separated by spacers and mounted on horizontally oriented rods. The spacing between the blades forming the intake rack is selected to screen debris of the desired size from entering the water intake of the system or facility that the trash rack is protecting, without significantly reducing water flow into the water intake. Such intake racks may be made of metallic or non-metallic materials. Intake racks of this type are available, for example, from Hydro Component Systems, LLC of Watertown, Wis. and covered by U.S. Pat. No. 7,815,811, incorporated by reference herein in its entirety.
As an intake rack or other screening structure prevents the flow of debris into the water intake of a system or facility from an exposed above-ground water source, the debris being screened will build up on the intake rack or other screening structure. This accumulating debris must be cleared from the intake rack or other screening structure on a regular basis, to prevent the buildup of such debris from interfering with the flow of water into the system or facility water intake.
A typical tool for removing accumulated debris from an intake rack is known as a trash rake. A typical trash rake can include a rake-like structure including tines that are spaced apart so as to fit between the blades of an intake rack to be cleaned. This rake-like structure is positioned adjacent to and drawn vertically along the intake rack blades to remove accumulated debris therefrom.
Such trash rake systems typically include a main unit which is positioned above the intake rack and movable relative thereto on tracks or the like. A telescoping boom assembly is mounted to the main unit. A rake head assembly is attached to an end of the telescoping boom. The telescoping boom moves the rake head assembly vertically along the rack system to rake up and collect the debris trapped thereon. The boom is also movable relative to the main unit to position the rake head assembly over a conveyor or other collection structure so that trash collected by the rake head assembly may be dumped onto the collection structure. An exemplary embodiment of such a trash rake system may be readily seen at U.S. Pat. No. 7,815,811 incorporated by reference above.
This dumping operation typically involves rotating the rake head assembly relative to the telescoping boom to dump trash collected by the rake. The applicant herein, however, has discovered several problems with this existing dumping operation, and particularly the mechanism responsible for manipulating the rake head assembly to achieve the dumping operation.
More specifically, the dumping operation is typically effectuated by use of hydraulics, in a similar fashion as the hydraulic manipulation of a bucket on an excavator or the like. Alternatively, complex cable driven or gravity driven mechanisms may also be utilized. The particular use of hydraulics, however, may lead to inadvertent contamination of the water within which the trash rake operates in the event of a hydraulic fluid leak. Further, the hydraulics are specifically needed just for the dumping operation, thereby driving up the cost and complexity of the system. Further still, the cable or gravity driven mechanisms are also complex in their design.
Yet further, such existing systems suffer from the problem of residual trash entrapment behind the rake head assembly after it has rotated to dump the trash within the rake head assembly. This residual trash must be manually cleared away from behind the rake head assembly to allow it to rotate back to its working, non-dumping orientation.
Yet further, such existing systems have a generally limited range of motion with respect to their rake head assembly. That is, the rake head assembly may only rotate between about zero and less than ninety degrees about its axis of rotation when conducting the above described dumping operation. This limited range of rotation undesirably prevents all of the trash from falling out of the rake head assembly during the dumping operation. This residual trash left within the rake head assembly must also be manually removed therefrom.
Accordingly, there is a need in the art for a trash rake system which employs a rake head assembly which overcomes the problems identified above. Specifically, there is a need in the art for a trash rake system which employs a rake head assembly which employs a drive mechanism which provides a low risk of water contamination, a high degree of angular articulation, and a reduction or elimination of the need to manually remove residual trash as identified above. The invention provides such a trash rake system. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.